View Compilation Error

0_0_6310474_23599.cpp: In function `int main()':
0_0_6310474_23599.cpp:4: error: `_int64' undeclared (first use this function)
0_0_6310474_23599.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6310474_23599.cpp:4: error: expected `;' before "m"
0_0_6310474_23599.cpp:5: error: `m' undeclared (first use this function)
0_0_6310474_23599.cpp:5: error: `n' undeclared (first use this function)
0_0_6310474_23599.cpp:7: error: `sum' undeclared (first use this function)